Gasoline motor fuel composition



United States Patent 3,332,756 GASOLINE MOTOR FUEL CGMPOSITION John F.Definer, Glenshaw, Pa., assignor to Gulf Research & Development Company,a corporation of Delaware No Drawing. Filed June 13, 1963, Ser. No.287,488 4 Claims. (Cl. 44-69) This invention relates to fuels and moreparticularly to leaded gasolines for high-compression, spark ignitionengines.

It has long been recognized that for greater economy with respect tofuel requirement and greater efficiency in the operation of agasoline-powered, spark ignition engine, high compression ratios aredesired. As a result, several automobile manufacturers have increasedthe compression ratios of their spark ignition engines to 8.5:] and evenas high as 10.5:1, the future trend of the automotive industryindicating that substantially all engines will be operating at such highor higher compression ratios in the foreseeable future. In order toobtain smooth engine operation at these high compression ratios undervarious driving conditions it is necessary to employ a fuel having highoctane numbers as determined by both the motor method (ASTM: D357-53)and the research method (ASTM: D908-55).

Smooth operation at high speeds under open-road conditions in modernhigh-compression engines usually requires a fuel having a motor octanenumber of at least about 85. Smooth operation in the same engines atlower speeds under city driving conditions where frequent ac celeratiousare encountered usually requires a fuel having a research octane numberof at least about 95. An optimum fuel for present day use is thus onewhich has a research octane number of at least about 95 and asensitivity of about 8 to 12. By sensitivity, I intend to indicate thespread or differential between the octane numbers as determined by themotor method and the research method. Of course, if fuels are availablewhose motor and research octane numbers coincide at levels of 95 ormore, the sensitivity of such fuels can be in the order of 1 to 2 orless and still result in desirable fuels for use in high-compressionengines under both low-speed and high-speed operation.

In order to obtain fuels having both high motor and high research octanenumbers the petroleum industry has developed numerous petroleumhydrocarbon conversion processes among which may be mentioned cracking,alkylation, aromatization, cyclization, isomerization, hydrogenation,dehydrogenation, hydroisomerization, polymerization,hydrodesulfurization, reforming, hydroforming, polyforming, Platformingand combinations of two or more of such processes. These processesproduce hydrocarbons boiling in the gasoline boiling range which haveengine performance characteristics markedly superior to the charge stockand to comparable boiling hydrocarbons found in straight-run gasolines.In general, straight-run gasolines are more parafiinic and less olefinicand aromatic than gasolines obtained, for example, by a crackingprocess. Straight-run gasolines, per se, even when fortified withtetraethyl lead generally do not give the high motor and research octanenumbers required for smooth performance in present day engines. Thisinvention is concerned primarily, therefore, With fuels or a blend offuels obtained by one or more of the above-mentioned hydrocarbonconversion processes. However, a small amount of straight-run gasoline,in some instances, may be blended with the fuels obtained by aconversion process.

To improve still further the octane ratings of the fuels obtained by thevarious conversion processes, the petroleum industry, in most instances,has resorted to the use of various anti-knock agents among which istetraethyl 3,332,756 Patented July 25, 1967 lead. While the addition oftetraethyl lead to gasolines obtained by one or more conversionprocesses improves their motor and research octane numbers, theresulting fuels have certain disadvantages arising from the presence ofthe lead. One of the chief objections to the use of gasolines containingtetraethyl lead, i.e., leaded gasolines, arises from the tendency ofsuch fuels upon being burned to form decomposition products oftetraethyl lead, a portion of which products are deposited on the wallsof the combustion chambers of the engine and on the electrodes andinsulators of the spark plugs, thus reducing the efficiency of theengine and offsetting to some extent the increased efiiciency obtainedby using an engine having a high compression ratio.

In an attempt to overcome the detrimental effect of the deposits oftetraethyl lead decomposition products in an engine, various scavengingagents have been added to the fuel to change the form of the tetraethyllead decomposition products to those which are more volatile and thusless likely to be deposited Within the engine. For example, variousvolatile alkyl halides such as ethylene dibromide and/or ethylenedichloride have been used with tetraethyl lead to produce thecorresponding halides of lead which are more volatile than the oxides.The volatile alkyl halides, however, have not completely overcome thedeposition of the decomposition products. The decomposition productscomprise various salts including the oxides, sulfates, bromides andchlorides of lead. These decomposition salts deposited within thecombustion chamber of the engine have been found to alter adversely theengine operation. The adverse effect encountered as a result of thedeposits of the decomposition salts is frequently evidenced by engineknocking. The knocking thus encountered is that associated withpreignition of the fuel in the combustion chamber of a spark ignitionengine. This knocking associated with preignition should not be confusedwith knocking due to explosive autoignition of the unburned portion ofthe fuel-air mixture to be traversed by the normal flame from the sparkplug.

I have found that the decomposition salts deposited within thecombustion chamber of a high-compression, spark ignition engine can bemodified to reduce their tendency to promote or initiate preignition ofthe motor fuel in the engine by incorporating in the motor fuel a smallamount of a metal carbonyl selected from the group consisting ofmolybdenum hexacarbonyl and tungsten hexacarbonyl. Thus, in accordancewith the present invention an improved gasoline motor fuel compositioncomprises a major amount of a gasoline containing tetrae'thyl lead in anamount sufiicient to produce a gasoline fuel composition having a motoroctane number of at least about and a research octane number of at leastabout 95, said gasoline fuel composition upon combustion normallytending to form deposits which induce preignition of the gasoline in thecombustion chamber of a high-compression, spark ignition engine and asmall amount, sufficient to substantially reduce such preignition, of ametal carbonyl, selected from the group con sisting of molybdenumhexacarbonyl and tungsten hexacarbonyl.

The hexacarbonyls of molybdenum and tungsten are available commerciallyand thus their preparation, per se, constitutes no part of the presentinvention. They can readily be prepared, for example, by reacting a saltof the metal such as tungsten hexachloride with carbon monoxide and areducing metal such as aluminum in the presence of a catalytic amount ofa metal alkyl such as triethyl aluminum. The reaction is conducted attemperatures up to about 200 C. and at pressures up to about 5,000pounds per square inch.

The amount of the hexacarbonyl of molybdenum or tungsten employeddepends upon the tetraethyl lead content of the fuel. For this reason,the amount is more significant and is more accurately expressed in termsof that amount which theoretically would be required if all of the leadintroduced into the fuel in the form of tetraethyl lead were to beconverted to lead molybdate or lead tungst-ate assuming 100 percentconversion. While improved results can be obtained in some instanceswith amounts corresponding to at least about 0.05 times thattheoretically required to convert the lead to lead molybdate or leadtungstate, it is ordinarily preferred to use amounts above about 0.1theory. Especially good results are obtained by using about 0.2 timesthe theoretical amount required. In general, I prefer to use an amountnot more than about 0.3 times the theoretical amount required to convertall of the lead to lead molybdate or lead tungstate. Amounts greaterthan 0.3 times the theoretical amount can be employed, but for economicreasons, I prefer to use only the amount required to give the desiredimprovement. Amounts in the order of at least about 0.005 theory can beemployed when another ignition control agent, such as anorgano-phosphorus compound, is also present in amounts of 0.1 to 0.5theory. The metal carbonyls at lower concentrations have less tendencyto adversely affect the octane rating of the leaded gasoline in whichthey are incorporated. Therefore, I prefer to employ the least amount ofmetal carbonyl required to give the desired improvement within the rangeof about 0.05 to about 0.3 times that theoretically required to convertthe lead to lead molybdate or lead tungstate. In view of the fact thatthe amount of tetraethyl lead in the gasoline varies from one fuel toanother, it is difiicult to state on a weight basis the amount of thehexacarbonyl compound based upon the weight of the gasoline. However,once knowing the amount of tetraethyl lead present in the gasoline, itis an easy matter to calculate the amount of the hexacarbonyl compoundrequired on a weight basis. Most gasolines on the market today containbetween about one and about three cubic centimeters of tetraethyl leadper gallon of gasoline. Based upon a gasoline having a gravity of about54 API and containing about one cubic centimeter of tetraethyl lead, Ihave determined that the amount of molybdenum hexacarbonyl correspondingto 0.05 to 0.3 theory is about 0.002 to about 0.014 percent by weightbased on the gasoline. To incorporate 0.05 to 0.3 theory of tungstenhexacarbonyl in the same gasoline would require about 0.003 to about0.019 percent by weight based on the gasoline. If the gasoline contains3 cubic centimeters of tetraethyl lead, then the molybdenum hexacarbonylfor 0.05 to 0.3 theory is about 0.007 to about 0.042 percent by weight.In this case, the tungsten hexacarbonyl would correspond to about 0.009to about 0.056 percent by weight. Thus, the normally usefulconcentration range for a 54 API gasoline containing about 1 to about 3cubic centimeters of tetraethyl lead is about 0.002 to about 0.06percent. It will be understood, of course, that the optimum amount on aweight basis for molybdenum hexacarbonyl may not be the optimum amountfor tungsten hexacarbonyl. One reason for this is that the effectivenessof the compounds may vary. Another quite obvious reason is that themolecular weight of tungsten hexacarbonyl (352) is greater than themolecular weight of molybdenum hexaca-rbonyl (264). In any event, theamount of the molydenum hexacarbonyl or tungsten hexacarbonyl used issufficient to modify the decomposition salts deposited within thecombustion chamber of a high-compression, spark ignition engine toreduce their tendency to promote or initiate preignition of a gasolinecontaining tetraethyl lead and an ethylene halide in an amount normallytending upon combustion to form deposits which induce preignition of thegasoline in the combustion chamber of the engine.

The gasoline fuel composition to which the molybdenum hexacarbonyl ortungsten hexacarbonyl is added comprises a mixture of hydrocarbonsboiling in the gasoline boiling range having a motor octane number(leaded) of at least about and a research octane number (leaded) of atleast about 95. The mixture of hydrocarbons can be obtained by at leastone of the petroleum conversion processes including cracking,alkylation, aromatization, cyclization, isomerization, hydrogenation,dehydrogenation, hydroisomerization, polymerization,hydrodesulfurization, reforming, hydroforming, polyforming, Platforming,and combinations of two or more such processes, as well as by theFischer-Tropsch and related processes. While current straight-rungasoline has octane numbers too low to qualify as the sole hydrocarboncomponent of gasoline fuel compositions within the scope of thisinvention, a small amount of straight-run gasoline can be blended withthe hydrocarbon mixture obtained by one or more of the designatedconversion processes provided the resulting mixture has a motor octanenumber (leaded) of at least about 85 and a research octane number(leaded) of at least about 95. A preferred gasoline fuel compositioncomprises a blend of hydrocarbons obtained by catalytic cracking,Platforming and alkylation processes.

In addition to the molybdenum or tungsten hexacarbonyl and tetraethyllead, the gasoline fuel composition of my invention can contain othergasoline improvement agents including upper cylinder lubricants,corrosion and oxidation inhibitors, conventional alkyl halide leadscavenging agents, alcoholic anti-stalling agents, metal deactivators,dehazing agents, anti-rust additives, other ignition control agents,dyes and the like.

In a preferred embodiment of the invention, about 0.02 to about 0.1theory of the metal hexacarbonyl is employed in conjunction with about0.1 to about 0.5 theory of a phosphorus-containing ignition controlagent. For example, about 0.02 to about 0.1 theory of tungsten ormolybdenum hexacarbonyl is employed together with about 0.1 to about 0.5theory of an organo-phosphorus compound such as tricresyl phosphate,cresyl diphenyl phosphate, methyl diphenyl phosphate,tri(n-butyl)phosphate, vtri(butoxyethyl)phosphate, tributyl phosphite,trimethylphosphite, tributyl phosphine, and the like. When molybdenum ortungsten hexacarbonyl and tri(butoxyethyl)phosphate are used together,the molybdenum or tungsten hexacarbonyl is preferably employed inamounts corresponding to about 0.02 to about 0.1 theory and thetri(butoxyethyl)phosphate in an amount corresponding to about 0.1 toabout 0.2 theory; 7

When an upper cylinder lubricant is employed it is generally used in anamount of from about 0.25 to about 0.75 percent by volume of thecomposition, e.g., 0.5 volume percent. This oil should be a lightlubricating oil distallate, e.g., one having a viscosity at F. of fromabout 50 to about 500 Saybolt Universal seconds, e.g., about 100 SUS.Although highly parafiinic lubricating distillates can be used,lubricating distillates obtained from Coastal or naphthenic type crudeoils are preferred because of their superior solvent properties. Thelubricating oil can be solvent-treated, acid-treated or otherwiserefined.

When an oxidation inhibitor is desired any of the conventionalinhibitors can be utilized. The alkylated phenols, e.g.,2,4,6-tri-tertiary-butylphenol, 2,6-di-tertiarybutyl-4-methylphenol,2,2-bis(2-hydroxy-3-tertiary butyl- 5-methylphenyl)propane andbis(2-hydroxy-3 tertiarybutyl-5-methylphenyl )methane, because of theirhydrocarbon-solubility and water-insolubility characteristics arepreferred oxidation inhibitors. Such inhibitors when used areincorporated in the gasoline fuel composition in amounts of from about0.001 to about 0.02 percent by Weight of the composition, e.g., 0.007weight percent.

Exemplary of other specific improvement agents which can be used areN,N-disalicylidene-l:2-diaminopropane as a metal deactivator and thecocoamine salt of diisooctyl acid orthophosphate as a rust inhibitor.The metal deactivator is generally used in small amounts of the order ofabout 0.0003 to about 0.001 percent by weight based on the fuelcomposition. The rust inhibitor is generally used in small amounts ofthe order of about 0.002 to about 0.008 percent by weight based on thefuel composition.

The molybdenum and tungsten hexacarbonyls present no particular problemwith respect to their addition to gasoline. While the hexacarbonyl canbe added directly to the gasoline, one convenient method of adding it tothe fuel is to form a concentrate thereof with a liquid solvent andthereafter adding the concentrate to the fuel. Any so1- vent which doesnot adversely affect the desirable properties of the fuel can be used.Suitable solvents include mineral oil, gasoline, naphtha, Stoddardsolvent, mineral spirits, benzene, heptane, kerosene, toluene, ethylalcohol, isopropyl alcohol, isooctyl alcohol, decyl alcohol, methylal,acetal, propylal and isopropylal, tetraethoxy propane, dimethyl acetalof isooctyl aldehyde, ethyl ether, cyclohexanol, acetone, analkoxyalkanol, or the like. The concentrate, of course, can containother conventional gasoline improvement agents, such as anti-oxidants,typical anti-stalling agents, anti-knock agents, a metal deactivator, anupper cylinder lubricant, an alkyl halide lead scavenging agent, adehazing agent, anti-rust additives, other ignition control agents, dyesand the like. Since the amount of hexacarbonyl employed depends upon theamount of the tetraethyl lead present, this method of adding thecompound to the gasoline serves as a convenient way of adding thecorrect amount of hexacarbonyl and tetraethyl lead simultaneously. Thus,a gasoline-benefiting concentrate can be made by admixing tetraethyllead or commercially availablemixtures of tetraethyl lead and a halideof ethylene and a solvent such as benzene or toluene with the molybdenumor tungsten hexacarbonyl wherein the hexacarbonyl is present in anamount between about 0.05 and about 0.3 times the theoretical amountrequired to convert the lead of the tetraethyl lead to lead inolybdateor lead tungstate.

One convenient method of preparing a gasoline-benefiting concentrate isto start with a commercially available product comprising tetraethyllead and the halides of ethylene. One such commercially availableproduct consists of about 61.5 percent by weight of tetraethyl lead,about 17.9 percent by weight of ethylene dibromide, about 18.8 percentby weight of ethylene dichloride and about 1.8 percent by weight ofkerosene. This commercially available product has a specific gravity of1.587 at C.

A typical gasoline-benefiting concentrate wherein the molybdenumhexacarbonyl is present in an amount corresponding to 0.2 times thetheoretical amount required to convert the lead to lead molybdate isprepared by incorporating 5.06 cubic centimeters of the commerciallyavailable product designated hereinabove in a toluene or benzenesolution containing 0.81 grams of molybdenum hexacarbonyl. 5 .06 cubiccentimeters of the commercially available product contains 3 cubiccentimeters of tetraethyl lead.

The amount of the gasoline-benefiting concentrate added to gasoline willvary depending upon the octane improvement desired. Ordinarily, however,the concentrate is added in an amount sufficient to incorporate betweenabout one and about three cubic centimeters of tetraethyl lead in agallon of gasoline.

The gasoline compositions of this invention and their preparation areillustrated in detail by the following specific examples.

EXAMPLE I A gasoline composition having excellent preignitioncharacteristics is prepared by incorporating 0.813 grams 'of molybdenumhexacarbonyl in a gallon of the base gasoline (approximately 0.028weight percent). The base gasoline is a blended gasoline made up ofcatalytically cracked gasoline, alkylate and Platformate. The basegasoline contains about 3 cubic centimeters (4.94 grams) of tetraethyllead per gallon of gasoline. In addition, the base gasoline contains asan oxidation inhibitor 2,6- di-tertiary-butyl-4-methylphenol (30lbs/1000 bbls.) and as a metal deactivatorN,N-disalicylidene-1:Z-diaminopropane (1 lb./ 1000 bbls.). Themolybdenum hexacarbonyl thus comprises about 0.2 times the theoreticalamount required to convert the lead of the tetraethyl lead to leadmolybdate.

EXAMPLE II Another composition is prepared in the manner of theforegoing Example I by incorporating 1.083 grams of tungstenhexacarbonyl in a gallon of the base gasoline (approximately 0.038weight percent). The tungsten hexacarbonyl thus comprises about 0.2times the theoretical amount required to convert the lead to leadtungstate.

Typical properties of the base gasoline and the base gasoline containing0.2 theory of molybdenum hexacarbonyl and tungsten hexacarbonyl are asfollows:

Base Gaso- Base Gaso- Base Gasoline plus line plus line 0.2 Theory 0.2Theory Molyb- Tungsten denuin Hexa- Hexacarbonyl carbonyl Gravity, API55.4 55 A 55.5 Sp. Gr., 60l00 F 0.7571 0.7571 0.7567 Sulfur, L, Percent0 .040 0 .039 0039 Copper Strip Test, 122 F., 3 111-5.. 1 1 1 CopperDish Gum, rug/ ml.

(AS'IM: D910-53T) 20 15 20 Existent Gum, mg./100 m1. 2 5 9 OxidationStability, min 1, 064 1,198 1, 201 Bromine No 29 .7 29 .3 29 .6 KnockRating;

Motor Method 88.9 87 .7 87 .9 Research Method 100 .7 99 .8 99 .8 TEL,ml./gal 30.08 3 .12 3 .07 Vapor Pressure Reid, lb 6 .0 6 .0 6 .0Distillation, Gasoline;

Over Point, F 108 110 113 End Point, F 381 380 385 10% Evap. at F- 154100 50% Evap. at F 253 244 252 90% Evap. at F--- 328 321 327 Recovery 98.2 98 .0 97 .2 Residue 0.8 0.8 1.0

EXAMPLE III Another composition is prepared in the manner of theforegoing Example I by incorporating 0.406 grams of molybdenumhexacarbonyl in a gallon of base gasoline (approximately 0.014 weightpercent). The molybdenum hexacarbonyl thus comprises about 0.1 times thetheoretical amount required to convert the lead to lead molybdate.

EXAMPLE IV An additional composition is prepared in the manner of theforegoing Example I by incorporating 0.203 grams of molybdenumhexacarbonyl in a gallon of gasoline. The molybdenum hexacarbonyl thuscomprises about 0.05 times the theoretical amount required to convertthe lead to lead molybdate.

EXAMPLE V An additional gasoline composition having improved preignitioncharacteristics combined with good uppercylinder lubrication is preparedby adding a lubricating oil distillate to the base gasoline and thenincorporating in the oil-containing gasoline fuel composition 0.813grams of molybdenum hexacarbonyl per gallon of gasoline fuel composition(approximately 0.028 weight percent). The molybdenum hexacarbonyl thuscomprises about 0.2 times the theoretical amount required to convert thelead to lead molybdate. The base gasoline used prior to the addition ofthe additives is the same as that used in Examples I through IV. Theoil, a light Coastal type (Texas) lubricating distillate oil, is addedto the base gasoline in the amount of 0.5 percent by volume(approximately 0.6 percent by weight) in order to form theoil-containing gasoline fuel composition. Typical properties of thelubricating distillate oil are as follows:

Gravity, API 24.5 Lbs./gal., 60 F. 7.55

Viscosity, SUS:

210 F 38.3 Viscosity Index 16 Flash; P-M: F. 315 Flash, 0C: F. 320 Fire,0C: F 355 Pour: F. 60 Color, ASTM Union 2.0 Carbon Residue, Conradson:percent 0.02 Copper Strip Test, 212 F., 3 hr. O Neutralization ValueASTM D974-51'I1 Total Acid No 0.05

EXAMPLE VI EXAMPLE VII Another composition having excellent preignitioncharacteristics is prepared in the manner of the foregoing Example I byincorporating in a gallon of the base gasoline 0.406 grams (0.1 theory)(approximately 0.014 weight percent) of molybdenum hexacarbonyl and0.831 grams (0.2 theory) (approximately 0.029 weight percent) oftri(butoxyethyl) phosphate.

EXAMPLE VIII Another composition is prepared in the manner of theforegoing Example I by incorporating in a gallon of the base gasoline0.54 grams (0.1 theory) (approximately 0.019 weight percent) of tungstenhexacarbonyl and 0.831 grams (0.2 theory) (approximately 0.029 weightpercent) of tri (butoxyethyl)phosphate.

EXAMPLE IX Another satisfactory composition is prepared as indicated inExample VIII except that 0.27 grams (0.05 theory) of tungstenhexacarbonyl is used with 0.2 theory of tri (butoxyethyl)phosphate.

EXAMPLE X Another satisfactoryrcomposition is prepared as indicated inExample VIII except that 0.135 grams (0.025 theory) of tungstenhexacarbonyl is used with 0.2 theory of tri(butoxyethyl) phosphate.

EXAMPLE XI Another satisfactory composition is prepared as indicated inExample VIII except that 0.054 grams (0.01

theory) of tungsten hexacarbonyl is used with 0.2 theory of tri(butoxyethyl) phosphate.

'8 EXAMPLE XII.

Another satisfactory composition is prepared as indicated in Example VHIexcept that 0.276 grams (0.1 theory) of methyl diphenyl phosphate isused with 0.1 theory of tungsten hexacarbonyl.

An appreciable reduction in preignition due to tetraethyl leaddecomposition product deposits is achieved by the use of the foregoinggasoline fuel compositions in internal combustionv engines of thegasoline-powered, spark ignition type. For example, when thecompositions described in the examples are burned in an internalcombustion engine operated under conditions wherein noise, includingpreignition, knock or rumble would normally be encountered such enginenoise is markedly less than the noise encountered when the base gasolineis used alone.

In order to illustrate the improved preignition characteristics obtainedwith a fuel of the invention as determined by the wild ping count, thebase gasoline was compared with compositions of the invention in asingle cylinder CF-R engine having a 7 to 1 compression ratio. Theengine installation used was a modification of the standard ASTMassembly as described in the laboratory knock-rating test procedure CRCdesignation F-l-545 and CRC designation F-2-545. These tests aredescribed in the CRC Handbook, 1946 edition, complied by theCoordinating Research Council, Incorporated. The engine assembly wasmodified to the extent that the Waukesha CFR engine was equipped with anL-head cylinder instead of an overhead valve.

The engine was operated on a cycling schedule alternating between thefollowing conditions:

Humidity Control- 1 TD C-Top Dead Center. 2 Ice Tower.

0ver the entire test, a period of about 6 days, a record is kept of thetotal number of wild pings encountered.

The total number of wild pings encountered during the test period isindicative of preignition tendencies. To determine the total number ofwild pings, the engine is equipped with an ionization gap andanelectronic wild ping counter which records the total number of wildpings encountered during the test period. Control tests are madeperiodically inasmuch as the engine requirements have a tendency tochange as the engine becomes older. The test results obtained in thesingle-cylinder CFR engine are set forth in Table I.

The data in the foregoing Table I clearly indicate the improvementobtained in a single-cylinder engine having a compression ratio of 7 to1 when a small amount of molybdenum hexacarbonyl is added to the basegasoline.

Additional single-cylinder tests were made using a commercial enignehaving a compression ratio of 9 to 1. The results of these tests are setforth in Table II.

The data in the foregoing Table II clearly indicate the improvementobtained in a single-cylinder engine having a compression ratio of 9 to1 when a small amount of molybdenum or tungsten hexacarbonyl is added tothe base gasoline.

In order to illustrate still further the improved engine operatingcharacteristics obtained with fuels of the invention, a test wasemployed in which the fuel was burned in commercially availablemulticylinder spark-ignition engines having compression ratios of 10 to1 and 10.5 to 1. In this test, the engines are operated on a cyclingschedule consisting of three minutes at 1500 r.p.m. at a 15 brakehorsepower load, followed by a one-minute idle at 450 r.p.m. The sparkadvance is the manufacturers setting. The coolant temperatures in andout are 150 and 160 F. (i-5), respectively. The oil temperature is 180F. (15). At the end of each twentyfour hours under the above-describedcycling schedule, noise requirement determinations are made. After thenoise requirement determinations are made, the engines are then put backon the cycling schedule for another twenty-four hours. The cycling andnoise requirement tests are continued for nine 24-hour periods or lessif an equilibrium octane number requirement appears to have beenreached.

The noise requirement determinations are made according to threesuccessive steps. If noise is encountered in step one, then steps twoand three are omitted. If noise is encountered in step two, the onlystep three is omitted. Noise in this test is intended to includepreignition, normal knocking or rumble. The three successive steps ofthe test are as follows:

(1) At a speed of 1100 r.p.m. the throttle is opened to detent (that is,the rear barrels of the carburetor are just open) at l-inch Hg intakemainfold vacuum.

(2) The engine speed is increased to 1300 r.p.m. at 3-inch vacuum.

(3) The engine is accelerated at -inch vacuum from 1300 to 2000 r.p.m.,standard spark, and held at this setting for 3 seconds (throttlewide-open at end of 3- second period).

Aural observations are made at steps (1), (2) and (3) and preignition,rumble and knock are recorded.

Ratings are made on the tank fuel (99 research octane number) and theactual noise requirement determined by the use of a set of commercialreference fuels up to an octane number of 113.5. For noise requirementsin the range 113.5 to 120, leaded isooctane is used. Octane numbersabove 100 are expressed in the approved extension scale, Wiese octanenumbers, which are:

Performance No. 100 3 an upper cylinder lubricant and a corrosioninhibitor are also shown.

TABLE III.AVERAGE OCTANE NUMBER REQUIREMENT TO PREVENT ENGINE NOISEEngine Fuel Composition Base Gasoline 120+ 120-]- Base Gasoline plus 0.1theory of tungsten hexacarbonyL 120+ Base Gasoline plus 0.2 theory oftri(butoxyethyl)phosphate 116+ Base Gasoline plus 0 3 theory oftri(butoxyethyl)phosphate Base Gasoline plus 0.2 theory of molybdenumhexacarbonyl (Example I composition) 117 Base Gasoline plus 0.2 theoryof tungsten hexacarbonyl (Example II composition) 104 Base Gasoline plus0.1 theory of molybdenum hexacarbonyl and 0.2 theory oftri(butoxyethyl)phosphate (Example VII composition) 114 Base Gasolineplus 0.1 theory of tungsten hexacarbonyl and 0.2 theory oftri(bntoxyethyl)phosphate (Example VIII composition) 104 Base Gasolineplus 0.05 theory of tungsten hexacarbonyl and 0.2 theory oftri(butoxyethyl)phosphate (Example IX composition) 101 Base Gasolineplus 0.2 theory of molybdenum hexacarbonyl, 0.5 vol. Percent CoastalLubricating Oil and 5 pounds per 1,000 barrels of gasoline of theeocoaminc salt of diisooetyl orthophosphoric acid (Example VIcomposition) 116 Engine A 10:1 Compression Ratio Engine B 10.5:1Compression Ratio The data in the foregoing Table II clearly indicatethe improvement obtained in multicylinder engines having compressionratios of 10 to 1 and 10.5 to 1 when a small amount of molybdenum ortungsten hexacarbonyl is added to a base gasoline alone or incombination with an organo-phosphorus compound. As indicatedhereinabove, it is ordinarily preferred to use amounts of metalhexacarbonyl above about 0.1 theory unless the metal hexacarbonyl isused in combination with another ignition control agent. In this regard,it will be noted from the data in Table III that 0.1 theory of tungstenhexacarbonyl gave not noticeable improvement in engine noise. When theamount was increased to 0.2 theory, the octane number requirementdropped to 104. When 0.1 theory of tungsten hexacarbonyl was used incombination with 0.2 theory of tri(butoxyethyl)phosphate the octanenumber requirement was also reduced to 104. The latter result issurprising since the improvement obtained is more than the additiveeifect of the two agents taken alone. It is also surprising to note thatstill further improvement is obtained when only 0.05 theory of tungstenhexacarbonyl is used together with 0.2 theory oftri(butoxyethyl)phosphate.

Additional noise requirement data were obtained in single cylinderengines having a 9.5 to 1 compression ratio and multicylinder engineshaving a 10.5 to l compression ,atio. In these determinations, leadedisooctane-benzene (LIB) ratings were obtained. The leadedisooctane-benzene rating, like the average octane number requirement toprevent engine noise, is also a rating of the fuel required to preventengine noise, including preignition, normal knocking and rumble. Thenumber signifying the LIB rating indicates the lowest percentage ofisooctane in a leaded isooctane-benzene mixture that can be burned inthe engine without inducing noise. Hence, a low LIB number indicates aneffective preignition additive. In this test the isooctane and benzeneeach contain 3 cc. of tetraethyl lead per gallon. Inasmuch as there islittle if any volume change on mixing benzene with isooctane, themixture is also assumed to contain 3 cc. of tetraethyl lead per gallon.The leaded isooctane-benzene ratings are shown in Table IV.

TABLE IV Engine Engine Engine A B Base Gasoline Base Gasoline plus 0.1theory of tungsten hexacarbonyl Base Gasoline plus 0.2 theory of tri-(butoxyethyl) phosphate Base Gasoline plus 0.3 theory of tri-(butoxyothyl) hosphate Base Gasoline p us 0.2 theory of tungstenhexacarbonyl (Example II com position) Base Gasoline plus 0.1 theory oftungsten hexacarbonyl and 0.2 theory of tri(butoxycthyl) phosphate(Example VIII composition) Base Gasoline plus 0.05 theory of tung stenhexacarbonyl and 0.2 theory of tri(butoxyethyl) phosphate (EXEIII' pleIX composition) Base Gasoline plus 0.025 theory of tungsten hoxacarbonyland 0.2 theory of tri(hutoxyethyl) phosphate (Example X composition)Base Gasoline plus 0.01 theory of tungsten hexacarbonyl and 0.2 theoryof tri(butoxyethyl) phosphate (Example XI composition) Base Gasolineplus 0.2 theory of methyl dipheuyl phosphate Base Gasoline plus 0.1theory of tungsten hexacarhonyl and 0.1 theory of methyl diphenylphosphate (Example XII composition) Engine A and Engine BSingle cylinderengines having a 9.5 to l compression ratio.

Engine C-Mnltioylinder engine having a 10.5 to 1 compression ratio.

The single cylinder engines (Engines A and B) data in the foregoingTable IV clearly show the improvement obtained in the leadedisooctane-benzene rating when 0.025 to 0.1 theory of tungstenhexacarbonyl is admixed with 0.1 to 0.2 theory of an organo-phosphoruscompound. It will be noted from the multicylinder engine (Engine C) datain Table IV that 0.1 theory of tungsten hexacarbonyl gave no noticeableimprovement in the LIB number. When the amount was increased to 0.2theory, the LIB number dropped to 66. When 0.1 theory of tungstenhexacarbonyl was used in combination with 0.2 theory of tri(butoxyethyl)phosphate the LIB number was 68. The latter result is surprising sincethe improvement obtained is more than the additive effect of using 0.1theory and 0.2 theory of tungsten hexacarbonyl and tri(butoxyethyl)phosphate, respectively. It is also surprising to note from themulticylinder engine data that the LIB number of the base gasolinecontaining 0.2 theory of tri(butoxycthyl) phosphate was reduced from 99+to 65 by the addition of only 0.05 theory of tungsten hexacarbonyl.

While my invention is described with reference to various specificexamples and embodiments, it will be understood that the invention isnot limited to such examples and embodiments and may be variouslypracticed within the scope of the claims hereinafter made.

I claim:

1. A gasoline motor fuel comprising a major amount of gasolinecontaining tetraethyl lead in an amount sufficient to produce a gasolinefuel composition having a motor octane number of at least about and aresearch octane number of at least about 95, said gasoline fuelcomposition upon combustion normally tending to form deposits whichinduce preignition of the gasoline in the combustion chamber of a sparkignition engine and a small amount, sufficient to substantially reducesuch preignition, of tungsten hexacarbonyl.

2. A gasoline motor fucl comprising a major amount of gasolinecontaining tetracthyl lead in an amount sufiicient to produce a gasolinefuel composition having a motor octane number of at least about 85 and aresearch octane number of at least about 95, said gasoline fuelcomposition upon combustion normally tending to form deposits whichinduce preignition of the gasoline in the combustion chamber of a sparkignition engine and a small amount, sufiicient to substantially reducesuch preignition of a synergistic mixture of an organo-phosphrousignition control agent and tungsten hexacarbonyl.

3. A gasoline motor fuel comprising a major amount of gasolinecontaining tetraethyl lead in an amount sufiicient to produce a gasolinefuel composition having a motor octane number of at least about 85 and aresearch octane number of at least about 95, between about 0.005 andabout 0.3 theory of tungsten hexacarbonyl and between about 0.1 andabout 0.5 theory of an organo-phosphorus ignition control agent.

4. A gasoline motor fuel comprising a major amount of gasolinecontaining tetraethyl lead in an amount suificient to produce a gasolinefuel composition having a motor octane number of at least about 85 and aresearch octane number of at least about 95, between about 0.02 andabout 0.1 theory of tungsten hexacarbonyl and between about 0.1 andabout 0.2 theory of tri(butoxyethyl) phosphate.

References Cited UNITED STATES PATENTS 1,779,061 10/1921 Danner et al.44-68 1,954,865 4/1934 Danner 4467 2,410,829 11/1946 Luten 44672,626,208 1/1953 Brown 44-73 2,654,697 10/1953 Andress et al. 44-582,818,416 12/1957 Brown ct al. 4468 2,863,742 12/1958 Cantrell et al.44-58 2,897,068 7/1959 Pellegrini et a1 44- 69 2,902,983 9/1959 Patberg44-67 2,982,627 5/1961 Lauer at al. 44-67 3,240,576 3/1966 Neu 4469DANIEL E. W'YMAN, Primary Examiner. Y. H. SMITH, Assistant Examiner.

1. A GASOLINE MOTOR FUEL COMPRISING A MAJOR AMOUNT OF GASOLINECONTAINING TETRAETHYL LEAD IN AN AMOUNT SUFFICIENT TO PRODUCE A GASOLINEFUEL COMPOSITION HAVING A MOTOR OCTANE NUMBER OF AT LEAST ABOUT 85 AND ARESEARCH OCTANE NUMBER OF AT LEAST ABOUT 95, SAID GASOLINE FUELCOMPOSITION UPON COMBUSTION NORMALLY TENDING TO FORM DEPOSITS WHICHINDUCE PREIGNITION OF THE GASOLINE IN THE COMBUSTION CHAMBER OF A SPARKIGNITION ENGINE AND A SMALL AMOUNT, SUFFICIENT TO SUBSTANTIALLY REDUCESUCE PREIGNITION, OF TUNGSTEN HEXACARBONYL.